Are you sure Block Power is black market exclusive? Because I read in the guide that it was supposedly dropped by direhorn, and I've been farming him to get that recipe for my justicar. I haven't been too concerned about it taking a lot of time, considering how long it took to get some of the potion recipes (a looong time).

I'm collecting all recipes on my warmage, but am still missing the block power on that toon too (the purchase only recipes not counted).

If someone from up high or with connections there can confirm that block power is indeed black market exclusive that would mean a lot to me and save me the time I would otherwise spend to try and get it to drop (I have so far spent about half a year trying to get it).